The invention relates to a process and machinery (Preheaters and Recycling Machine) for accurately heating, milling/profiling, handling and placement to grade of 100% Hot In-place Recycled (HIR) asphalt mixed with various types of rejuvenating fluids, liquid polymers and aggregates, with or without the addition of new, virgin asphalt (produced by a standard asphalt plant). The asphalt pavement is heated and softened by two or more Preheaters, physically scarified by one or more sets of carbide cutters (rakes), profiled and collected by mills, measured and mixed with rejuvenating fluid, polymer liquid (if required) and washed aggregate (if required) in a pug mill. The type, and amount of additives required to 100% HIR asphalt pavement is specified by pre-engineering using core samples taken from the asphalt pavement at regular intervals.
The 100% HIR of asphalt pavement is achieved by the addition of rejuvenator fluid, liquid polymers (if required) and washed aggregate (if required). Rejuvenator fluid must be accurately metered, as too much rejuvenator fluid will cause the recycled asphalt to bleed (rejuvenator fluid rising to the surface) softening the compacted surface. Too little fluid will not restore flexibility back into the recycled asphalt.
Liquid polymers such as Latex are added to increase the performance of the 100% recycled asphalt (Superpave specifications) by increasing flexibility while reducing rutting and cracking over a wider operating temperature range.
Adding aggregate (typically washed sand) during the 100% HIR process will modify the asphalt's physical properties and the air void ratio (percentage of air entrenched in the asphalt and generally specified at between 3-5%).
Adding rejuvenating fluid alone to the recycled asphalt will generally reduce the air-void ratio while adding washed sand tends to increase the air-void ratio. Adding aggregates that contain dust (unwashed) will generally reduce the air void ratio. Pre-engineering determines the correct specification and application rates for rejuvenating fluid, polymer liquid and aggregate. The Recycling Machine is designed with modular pin-on attachments for increased flexibility.